Aggregate metering and spreading system



July 7, 1970 J. H. HOLLAND AGGREGATE METERING AND SPREADING SYSTEM 3 Sheets-Shout Filed. NOV. 24. 1967 FIG.

INVENTOR ATTORNEY July 7, 1970 J. H. HOLLAND 3,519,169

AGGREGATE METERING AND SPREADING SYSTEM Filed Nov. 24. 1967 2 Sheets-Sheet 2 INVENTOR JOHN H. HOLLAND WW-rW ATTORNEY United States Patent $519,169 AGGREGATE METERING AND SPREADING SYSTEM John H. Holland, Norman, Okla, assignor to J. H. Holland Company, Norman, 0kla., a corporation of Oklahoma Filed Nov. 24, 1967, Ser. No. 685,645 Int. Cl. A01c /00 US. Cl. 222178 15 Claims ABSTRACT OF THE DISCLOSURE A vehicular aggregate spreader having a hopper for holding a supply of aggregate with an elongated slot of variable width extending across the bottom of the hopper and transversely of the vehicle. The slot is positioned above an elongated valve cavity in which an elongated rotating, vaned valve body is disposed. The elongated slot is defined by a series of pivotally supported, adjustable plates and by a pivotally supported scroll which also forms the back wall of the valve cavity. The adjustable plates permit the width of the slot to be varied to pass, by gravity, different sized aggregate at different rates, and a hydraulic cylinder pivots the scroll away from the adjustable plates and away from the valve body to pass oversized particles which may jam in the slot. This procedure also dumps an excess quantity of particles which may be used to cover over any voids caused by Oversized particles clogging a portion of the slot. During operation the vaned valve body is rotated at a speed which will result in cavitation so that the volume of aggregate will be determined by gravity flow through the slot. The vaned valve body is also rotated counter to the rotation of the support wheels of the spreader so that the aggregate will not have a rearwardly directed motion vector which would tend to cause ripples in the spread of aggregate. The vanes of the valve body are divided into longitudinal sections and are staggered in order to uniformly load the drive motor used to rotate the vaned valve body and prevent ripples in the aggregate spread due to stuttering movement of the valve body.

BACKGROUND OF THE INVENTION In US. Pat. No. 3,270,633, issued Sept. 6, 1966 to the present applicant, a paving machine is described in which heated liquid asphalt is sprayed on the ground by a spraybar located at the front of the machine. Crushed rock or aggregate is then spread from a hopper in a thin, uniform layer over the asphalt from an elongated slot located immediately behind the spraybar, and the aggregate is immediately pressed into the hot asphalt by the support wheels of the vehicle. Such a machine is capable of operating at much greater speeds than has heretofore been possible. Since the aggregate is immediately pressed into the hot asphalt, a much thinner layer of aggregate can be used to greatly reduce waste. As a result of these factors, the aggregate spreading system must very accurately meter the aggregate and deliver it uniformly with respect to time.

Previous systems have been troubled with periodic variations or waves in the thickness of the aggregate. These waves or ripples may have varying wavelengths and may result from various factors. Some systems use a vane feeder to meter the aggregate. Any eccentricity in the feeder tends to produce periodic ripples in the spread, particularly when handling fine aggregate.

Oversized particles or foreign objects in the aggregate tend to clog the slot through which the aggregate is dispensed, resulting in a streak of asphalt which is not cov- 3,519,169 Patented July 7, 1970 ered by aggregate. This is a particularly serious problem in the above mentioned paving machine because the only way the object can be removed is to stop the machine and dig the object out of the aggregate in the hopper.

An important object of this invention is to provide an aggregate distribution system which accurately meters the aggregate. This is achieved primarily by providing an elongated slot of variable width at the bottom of an aggregate hopper. The slot communicates with a valve cavity which is blocked by a rotary, vaned valve body. The vaned valve body is rotated at a speed sufficiently high to cavitate, so that aggregate is uniformly metered at a rate determined by the rate at which the particular sized aggregate will fall by gravity through the static slot.

Another object of the invention is to spread the aggregate evenly over the ground. In addition to uniform metering, this is achieved by rotating the vaned valve body in a direction counter to the rotation of the support wheels of the vehicle so that the vanes of the valve body will be moving in the same direction as the vehicle as they pass around the bottom of the valve body. If the aggregate is given a rearward velocity approaching the forward velocity of the vehicle, the aggregate impelled by each vane tends to drop vertically downwardly, resulting in a ripple pattern. In accordance with another aspect of the invention, a ripple pattern to form a Warning strip, if desired, may be produced by rotating the vaned valve body in the same direction of rotation as the support wheels.

In accordance with a more specific aspect of the invention, the elongated slot is formed by front and rear walls. The rear wall forming the slot also forms the rear wall of the valve cavity and may be pivoted away from the front wall and away from the valve body in order to permit oversized particles to clear the slot and valve body and also dump an excess volume of aggregate which may be used to cover over any parts of the coat which have been missed.

In accordance with another more specific aspect of the invention, the front wall of the slot is formed in a plurality of pivotally supported sections each of which is individually adjustable between a closed position and a full open position, thus permitting both the width and length of the slot to be adjusted.

In accordance with another specific aspect of the invenion, the vaned valve body is formed in a plurality of sections in which the vanes of each successive section are staggered to more uniformly load the drive motor and prevent stuttering movement of the valve body which would tend to result in ripples in the layer of aggregate.

A still more specific aspect of the invention concerns the specific structure of an aggregate receiving hopper embodying the above features.

BRIEF DESCRIPTION OF THE DRAWlNGS The novel features believed characteristic of this invention are set forth in the appended claims. The invention itself, however, as Well as other objects and advantages thereof, may best be understood by reference to the following detailed description of an illustrative embodiment, when read in conjunction with the accompanying drawings, wherein:

FIG. 1 is a side elevational view, partially broken away, of an aggregate distribution system in accordance with the present invention;

FIG. 2 is a rear elevational view of a portion of the aggregate distribution system shown in FIG. 1;

FIG. 3 is an isometric view, partially broken away, of a portion of the aggregate distribution system of FIG. 1;

FIG. 4 is a simplified plan view of the vaned valve body of the aggregate distribution system of FIG. 1; and

FIG. 5 is a schematic end view which serves to illustrate the operation of the aggregate distribution system of FIG. 1.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to the drawings, an aggregate distribution system in accordance with the present invention is indicated generally by the reference numeral 10. The aggregate distribution system is shown as a part of a paving machine of the type described in US. Pat. 3,270,633 The machine includes an aggregate receiving hopper 12 which is attached to the front of the vehicle chassis 14. A roller 16 is provided at the front of the hopper 12 for engaging and pushing the wheel 18 of a dump truck which dumps its load of aggregate into the hopper 12. An asphalt spraybar 20 is located beneath the front of the hopper 12 to cover the ground in advance of the machine with a coat of asphalt 21, and the asphalt is immediately covered with a layer of aggregate 22 dispensed from the system 10. The support wheels 24 of the vehicle 14, together with outrigger rollers 26 at the outer ends of the hopper 12, form a uniform compaction means which immediately presses the layer of aggregate 22 into the coat of asphalt.

The front and rear walls of the hopper 12 are supported by a plurality of vertically disposed rib plates 40 which extend longitudinally of the machine and at transversely spaced points to divide the hopper into a series of identical compartments. The rear ends of the rib plates 40 are welded to a vertically disposed plate (not illustrated) which is connected to the chassis of the vehicle so that the hopper is cantilevered from the front of the vehicle. A single plate 42 spans all of the rib plates 40 and forms the upper portion of the rear wall of the hopper. The plate 42 may be welded to each of the rib plates 40. A plate 43 is Welded across the forward ends of all of the rib plates 40. A front fioor plate 44 extends between and is welded to each adjacent pair of rib plates 40 to form the fioor of each compartment. A gusset plate 46 is welded betwen the bottom edge of the front plate 43 and a mid point of the floor plates 44 and between each of the rib plates 40 of each compartment to rigidify the structure.

A front wall plate 48 is disposed in each compartment and extends between the two rib plates 40 forming the compartment. Each of the front wall plates 44 is pivotally connected by a piano hinge 50 to the welded junction between the front plate 43 and the floor plates 44.

An elongated, transversely extending slot 60 in each compartment is defined by the rear edge of the front wall plate 48 and a rear scroll plate 62. The rear scroll plate 62 has configuration shown in FIG. 1 and extends between each adjacent pair of rib plates 40. A pair of plates 64 are welded to the edges of the rear scroll plate 62 to rigidfy the scroll plate. Each of the scroll plates 62 is pivotally mounted by a hinge 66 at its upper end.

The pivotal position of each of the front wall plates 48 can be adjusted to selectively vary the width of slot 60 by a threaded rod 52 having a hex head 54. Each of the rods 52 is threaded through a nut 56 welded to the inner face of the front plate 43. Each rod 52 extends through a fixed tubular sleeve 58 and through an opening in the respective floor plate 44 and engages the center of the respective front wall plate 48. As the threaded rod 52 is screwed into the nut 56, the plate 48 is pivoted upwardly about the pivot axis formed by the hinge 50 and moved closer to the rear scroll plate to reduce the width of the slot until it is closed, if desired.

The scroll plates 62 of all of the compartments may be simultaneously pivoted rearwardly about the hinge 66 by a mechanism including a hydraulic linear actuator 68 which is pinned to the chassis 114 at 70. The rod of the linear actuator 68 is pivotally connected to the crank arm 71 of a torque tube 72 by a pin located on the axis 73. The torque tube 72 is journaled in the rib plates 40 by bearings 74, as can best be seen in FIG. 2, and carries a crank arm 76 for each scroll plate 62. Each of the crank arms 76 is connected to the respective scroll plate 62 by an adjustable length clevis 78 and a bearing sleeve 80 which is journaled on a hinge pin 81 extending between the edge plates 64 of the scroll.

A valve cavity is formed immediately below the elongated slot 60 by the lower portion of the rear scroll plates 62 and a series of front scross plates 82. Each front scroll plate is welded along its upper edge to the floor plate 44 of the respective compartment and along its end edge to the rib plates 40 defining each compartment. Both the front scroll plate 82 and the lower portion of the rear scroll plate 62 have the same radius of curvature to form an elongated valve cavity of generally circular cross section extending transversely across the width of the hopper.

A vaned rotary valve body 84 is disposed in the valve cavity. The vaned valve body 84 is preferably comprised of a number of sections, one for each compartment. Each section is comprised of a tubular sleeve 86 having a length corresponding to the distance between the rib plates 40. A plurality of vanes 88 extend radially from the tube 86, and a pair of disks 90 are welded to the end of the sleeve 86 and to the ends of the vanes 88 to stiffen the assembly. The sleeves 86 are then slipped over a drive shaft 92 which extends from end to end of the hopper and are secured against rotation by some suitable means such as a set screw (not shown). The disks 90 are preferably one-half as thick as the rib plates 40 and are closely received in a circular opening cut in the rib plate 40 so as to prevent interflow of aggregate particles between adjacent compartments.

The shaft 92 is rotated in a counterclockwise direction, when referring to FIGS. 1 and 5, which is opposite to the direction of rotation of the support wheels 24 of the vehicle 14, by a suitable drive motor (not illustrated). This results in the vanes 88 moving in the same direction as the vehicle when the vanes pass beneath the shaft 92 and results in a forward velocity component being imparted to the aggregate 22 as it drops to the ground to provide beneficial results as will hereafter be described in greater detail. However, it is advantageous to use a reversible motor so that the valve body can be rotated in a clockwise direction when desired. The vaned rotary valve is rotated at at speed independent of the speed of the vehicle and at a speed sufiiciently great to cause cavitation. A hydraulic motor may be used for this purpose.

A powered helical auger 96 may be provided in the hopper above the slot 60 to distribute the aggregate more evenly over the transverse width of the hopper. This is usually desirable because the hopper is typically about fourteen feet wide and the aggregate is initially piled in the center of the hopper as it is dumped from the truck traveling in advance of the machine.

Prior to operation, the position of the front wall plates 48 in each compartment is adjusted by the respective threaded rod 52 to form a slot 60 of the desired width extending across the hopper. The length of the slot can be varied by moving selected plates 40 against the corresponding rear scroll plates to completely close the slot in the respective compartment. The width of the slot 60 will be selected so as to meter, by gravity, the desired rate of the particular sized aggregate which is to be spread. The width of the slot for a given sized aggregate can be determined using empirical methods. The clevises 78 will normally be adjusted such that the respective rear shroud plates 62 will barely clear the vanes of the valve body 84. However, if the size of the aggregate is large, it may be desirable to adjust the shroud 62 such that it clears the ends of the vanes 88 by an amount slightly less than the smallest dimension of the minimum sized particles of the aggregate.

After the aggregate has been dumped into the hopper from a dump truck, the auger 96 can be operated as required in order to distribute the aggregate over the length of the hopper. Until such time as the valve body 84 is rotated, no aggregate is dispensed because the vanes 88 of the valve body 84 in concert with the front and rear shroud plates 82 and 62 form a positive stop, although the portion of the valve cavity above the valve body will fill with aggregate.

When it is desired to spread aggregate, the valve body 84 is rotated counter to the rotation of the support wheels 24 of the vehicle at a speed sufficiently great that the chambers formed between the vanes 88 of the valve body do not fill, but cavitate. This insures that no aggregate stacks up immediately below the slot 60 and that the aggregate falls freely by gravity through the slot 60 at a uniform rate independent of the speed of rotation of the valve body 84. A typical speed of rotation is about 250 rpm.

As a result of the direction of rotation of the valve body 84, the particles are given a slight forward velocity component as they leave the lower end of the shroud 62. This velocity component plus the velocity of the vehicle causes the particles to impact the ground at a slight angle and spread uniformly over the layer of asphalt 21, thus eliminating the tendency to form ripples and providing a layer of uniform thickness. In the event it is desired to create uniformly repeated variations in the thickness of the aggregate layer, or ripples for an alert strip, the direction of rotation of the valve body 84 can be reversed. Then the aggregate will be given a velocity component counter to the velocity component resulting from motion of the vehicle so that each quantity of aggregate delivered in front of each vane 88 falls more nearly straight downwardly against the ground resulting in a minimum scattering. This produces a series of high and low spots in the layer of aggregate which is perpetuated as the aggregate is compressed into the hot asphalt. These strips can be used to alert drivers to a dangerous intersection or the like by a vibration and noise the frequency of which is determined by the spacing between the ridges and the speed of the automobile.

In the event an oversized stone, or other foreign object, lodges in the groove 60, the operator can actuate the hydraulic piston 68 in a manner to simultaneously pivot all of the rear scroll plates 62 away from the end of the front wall plates 48 and away from the vaned valve body 84, substantially to the position shown in dotted outline in FIG. 5, and then to immediately return the shrouds to the normal position. This not only results in clearing the oversized object, but also deposits an excess quantity of aggregate on the ground which may be used to manually cover any streaks of asphalt which may have been left bare as a result of the clogged slot. The excess aggregate will not stick to the layer of asphalt 21 and can be swept up. Since the valve body 84 continues to rotate during this period and aggregate continues to flow, the rear scrolls 62 can be returned to the normal position with a minimum of force. The curvature of the upper portion of the scroll 62 assists in this respect.

It will be noted that the rate at which aggregate is delivered is independent of any parameter other than the width of the slot 60 and the size of the aggregate. Thus, eccentricities in the valve body 84 have no effect upon the rate at which aggregate is delivered as in previous vane feeder systems. The staggered vanes of the valve body 84 produce a uniform load on the drive motor, thus eliminating stuttering movement of the valve body which would tend to cause ripples in the resulting aggregate layer. In addition, the valve body structure requires no precision parts and is therefore relatively economical to manufacture and assemble.

Although a preferred embodiment of the invention has been described in detail, it is to be understood that various changes, substitutions and alterations can be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

What is claimed is:

1. In a vehicular spreader for applying a uniform layer of aggregate to a roadbed, the aggregate metering system comprising:

a hopper for holding a volume of aggregate,

means forming an elongated slot of adjustable Width in the bottom of the hopper such that aggregate in the hopper will flow through the slot 'by gravity at a rate determined by the width of the elongated slot,

a valve cavity extending parallel to the elongated slot and disposed below the elongated slot such that aggregate falling through the. elongated slot will pass into the valve cavity, the valve cavity having front and rear walls defining an elongated outlet opening in the bottom thereof extending parallel to the elongated slot,

a vaned valve body rotatably mounted in the valve cavity and having vanes which are simultaneously disposed near both the front and rear walls to prevent the passage of aggregate between the valve body and the front and rear walls when the valve body is stationary, and

drive means for selectively rotating the valve body at a rate sufficiently great to :pass more than the volume of aggregate passing through the elongated slot by gravity whereby aggregate will be dispensed through the elongated outlet opening at a rate determined by the 'width of the elongated slot and independently of hte rate of rotation of the valve body.

2. The aggregate metering system defined in claim 1 wherein:

the drive means rotates the valve body in a direction such that the vanes pass the outlet opening traveling in the same direction as the vehicular spreader, and the valve cavity to the rear of the outlet opening is sloped forwardly.

3. The aggregate metering system defined in claim 1 wherein the means forming the elongated slot comprises: front wall means and rear wall means extending to adjacent positions to define the, width of the elongated slot, one of the wall means being pivotally supported along a pivot axis extending parallel to the elongated slot, and adjustment means for pivoting said one wall means about the pivot axis to selectively vary the width of the elongated slot.

4. The aggregate metering system defined in claim 3 wherein said one wall means is comprised of a plurality of sections each separately pivotable about a pivot axis, and the adjustment means is adapted to separately adjust each of the sections, each section of said one wall means being movable against the other wall means to close the elongated slot whereby the length of the elongated slot can be selectively changed.

5. The aggregate metering system defined in claim 3 wherein said one wall means is the front wall means.

6. The aggregate metering system for avehicular spreader comprising:

a hopper for holding a volume of aggregate, means forming an elongated slot of adjustable width in the bottom of the hopper such that aggregate in the hopper will flow through the slot by gravity at a rate determined by the width of an elongated slot, said means comprising front wall means and rear wall means extending to adjacent positions to define the width of the elongated slot, one of the wall means being pivotally supported along a pivot axis extending parallel to the elongated slot, and adjustment means for pivoting said one wall means about the pivot axis to selectively vary the width of the elongated slot, one of the wall means being pivotally mounted for 7 movement about a pivot axis extending parallel to the elongated slot, and means for selectively pivoting said one wall means about the pivot axis away from the other wall means to momentarily increase the width of the elongated slot to pass oversized particles and an excess quantity of aggregate,

a valve cavity extending parallel to the elongated slot and disposed below the elongated slot such that aggregate falling through the elongated slot will pass into the valve cavity, the valve cavity having an elongated outlet opening in the bottom thereof extending parallel to the elongated slot,

a vaned valve body rotatably mounted in the valve cavity to prevent the passage of aggregate through the valve cavity when the valve body is stationary, and

drive means for selectively rotating the valve body at a rate sufiiciently great to pass more than the volume of aggregate passing through the elongated slot by gravity whereby aggregate will be dispensed through the elongated outlet opening.

7. The aggregate metering system defined in claim 6 wherein said one wall means also forms a wall of the valve cavity toward which the top vanes of the valve body are rotated whereby oversized particles can pass between the valve body and valve cavity when said one wall means is pivoted away from the other wall means.

8. The aggregate metering system defined in claim 7 wherein said one wall means is the rear wall means.

9. The aggregate metering system defined in claim 6 wherein the means for selectively pivoting said one wall means is fluid powered.

10. The aggregate metering system for a vehicular spreader comprising:

a hopper for holding a volume of aggregate,

means forming an elongated slot of adjustable width in the bottom of the hopper,

a valve cavity extending parallel to the elongated slot and disposed below the elongated slot and having an elongated outlet opening in the bottom thereof extending parallel to the elongated slot such that aggregate falling through the elongated slot would pass through the valve cavity by gravity,

a vaned valve body rotatably mounted in the valve cavity for preventing the passage of aggregate through the valve cavity when the valve body is stationary, and

drive means for selectively rotating the valve body at a selected uniform rate whereby aggregate will be dispensed through the elongated outlet opening at a uniform rate.

11. The aggregate metering system defined in claim 10 wherein:

the drive means rotates the valve body in a direction such that the vanes pass the outlet opening traveling in the same direction as the vehicular spreader, and the valve cavity at the rear of the outlet opening is sloped forwardly.

12. The aggregate metering system for a vehicular spreader comprising:

a hopper for holding a supply of aggregate having a plurality of transversely spaced compartments each defined by a pair of vertically disposed rib plates extending longitudinally of the hopper, each compartment having front wall means and rear wall means sloping downwardly toward and defining a centrally located, transversely extending slot,

means forming a transversely extending valve cavity disposed below the slot such that aggregate falling through the slot will pass into the valve cavity, the valve cavity having an elongated outlet opening in the bottom thereof extending generally parallel to the slot,

a vaned valve body rotatably mounted in the valve cavity to prevent the passage of aggregate through the valve cavity when the valve body is stationary, and

drive means for selectively rotating the valve body of each compartment whereby aggregate in the hopper will be dispensed through the elongated outlet opening.

13. The aggregate metering system defined in claim 12 wherein:

the front wall means in each compartment includes a front wall plate extending between the rib plate defining the compartment, the front wall plate being pivotally supported at its front edge for pivotal movement about a horizontal, transversely extending axis, and the rear edge extending to and defining one edge of the slot, and

means for selectively varying the pivotal position of the front wall plate to selectively vary the width of the slot.

14. The aggregate metering system for a vehicular spreader defined in claim 12 wherein:

the valve cavity in each compartment is formed by a front scroll plate extending between the rib plates forming the compartment and a rear scroll plate extending between the rib plates forming the compartment, and

the scroll plate toward which the vanes at the top of the vaned valve body rotate is selectively movable away from the vaned valve body to pass oversized objects.

15. The aggregate metering system defined in claim 14 wherein:

the upper end of the movable scroll plate also defines the corresponding edge of the elongated slot whereby both the width of the slot and the spacing between the scroll plate and the valve body can be selectively increased to pass oversized objects.

References Cited UNITED STATES PATENTS 1,040,888 10/1912 Comrie 222-177 1,811,324 5/1931 Lockard 222-177 2,893,740 7/1959 Gaddis 222--177 2,904,224 9/1959 Young 222-178 3,010,612 11/1961 Steinle 222-178 X 3,072,290 1/1963 De Biasi 222178 X 3,228,310 1/1966 Cartwright 222178 X 3,395,834- 7/1968 Troy 222-504 X FOREIGN PATENTS 1,017,224- 1/1966 Great Britain.

ROBERT B. REEVES, Primary Examiner H. S. LANE, Assistant Examiner US. Cl. X.R. 222136, 285, 504 

